A conventional side-illuminating liquid crystal display device comprises a backlight module of the configuration as shown in FIG. 1. The backlight module comprises a light-guide plate 102, an optical film 103 provided on a side of the light emitting face 102b of the light-guide plate 102, and LED bar 101 provided on a side of the light incident face 102a of the light-guide plate 102. The LED bar 101 comprises several LEDs 101a disposed at the side thereof facing the light-guide plate 102, the light emitted from the LEDs 101a enters the light-guide plate 102 through the light incident face 102 of the light-guide plate 102 and then is guided to the optical film 103. Because the LEDs 101 usually are distributed separately along the length direction of the LED bar 101, hotspots causing uneven shade readily appears at the edge of the light-guide plate 102 adjacent to the light incident face 102a. When such a backlight module is used in the display device, the hotspots will spread from the non-displaying area to the displaying area of the display device, and then influence the display effect in the displaying area. When hotspot phenomenon occurs, it's generally required to regulate the grid point design of the light-guide plate, return the light-guide plate to its supplier for regulation, and the regulation period is relatively long, and the regulated effect is not good.